1. Field of the Invention
This invention relates to casings for rotating machinery and, more particularly, to split casings for use with gas compressors.
2. Brief Description of the Prior Art
FIG. 1 shows a prior art split casing section A for use with a gas compressor. The split casing section A includes a semi-cylindrical rolled plate B having two opposing edges C, Cxe2x80x2 and extending about a longitudinal axis X. A pair of flanges D, Dxe2x80x2 extend along each the opposing edges C, Cxe2x80x2 with each flange D, Dxe2x80x2 attached to the semi-cylindrical rolled plate B through welds E. The flanges D, Dxe2x80x2 define a plurality of bore holes F that extend from a top flange side G to a bottom flange side H.
Two of the prior art split casing sections A are traditionally joined together at their respective flanges D, Dxe2x80x2, forming a cylindrically shaped split case assembly. The split casing sections A are secured by fasteners, such as bolts, passing through the bore holes F. Rotating machinery components, such as compressor components, are then received within a cavity defined by inner surfaces of the joined split casing assembly.
One method for manufacturing a split casing section A is to roll a flat plate K (shown in FIG. 2), about the longitudinal axis X into a semi-cylindrical shaped rolled plate B. As shown in FIG. 3, flanges D, Dxe2x80x2 are then secured to the rolled plate B at edges C, Cxe2x80x2 through welds E (shown in FIG. 1). The bore holes F are drilled or formed in the flanges D, Dxe2x80x2 prior to welding the flanges D, Dxe2x80x2 to the rolled plate B or after the welding of the flanges D, Dxe2x80x2 to the rolled plate B.
The prior art split casing sections A shown in FIGS. 1 and 3 are expensive to manufacture due to numerous welds. Further, there always exists a possibility of failure due to improper welds between the flanges D, Dxe2x80x2 and the rolled plate B. Other prior art casing designs are shown in U.S. Pat. Nos. 1,352,276; 1,839,849; 2,683,017; 3,160,107; 3,390,830; 3,544,232; 4,137,006; 4,305,192; 4,551,065; 4,915,581; and, 5,063,661.
Therefore, it is an object of the present invention to provide a split casing section design that is less expensive to manufacture and does not require welded flanges.
The present invention is a casing design for rotating machinery, such as gas compressors or turbines, that generally includes a first casing section, a second casing section, and a plurality of fasteners. The first casing section is formed from a single plate into a substantially semi-cylindrical shaped shell having two opposing edges, two opposite external sides, and machined flanges. The second casing section is also formed from a single plate into a substantially semi-cylindrical shaped shell having two opposing edges, two opposing edges, and machined flanges. Opposing edges of each first casing section are aligned with corresponding opposing edges of each second casing section to form a substantially cylindrical structure held together by the plurality of fasteners. The fasteners pass through bore holes formed by each of the machined flanges.
A hollow receiving cavity is defined by inner surfaces of the joined first and second casing sections, as well as end plates joined to the first and second casing sections. The receiving cavity can receive rotating machinery components, such as compressor or turbine components.
The present invention is also a method for manufacturing a one-half section of a split casing assembly that includes the steps of:
a. providing a substantially semi-cylindrical casing section; and
b. forming flanges on opposite exterior sides of the semi-cylindrical section by removing material from the substantially semi-cylindrical shaped casing section. The method can also include the steps of,
c. forming a plurality of bore holes in the flanges;
d. forming port holes in the casing section;
e. connecting ports to the port holes; and
f. connecting the semi-cylindrical casing section to another semi-cylindrical casing section, forming a cylindrically shaped split casing assembly having a hollow receiving cavity in fluid communication with the ports.